Familiar enough to know that if he really would have aced the interview there's no way they would have dismissed him for that reason. The fact that he blatantly and hubristic claims he aced it adds to the warning signs.
While we are ignorant of your particular situation, by objective metrics, "aced the interview" is commonly defined as "they offered me a job for a salary higher than I had expected". Since they didn't offer you the job, presumably the others involved in the process did not come out of the interview thinking that you were the right person to hire.
It rings of hubristic delusion to claim that nonetheless, you "aced the interview". While hubristic delusion may in fact be the best attitude for self-advancement, depressive realists (likely in high representation on here on HN) might offer a more balanced "I thought I had aced the interview, but apparently the interviewers thought otherwise".
